For pathogenic mechanisms and biomarker discovery, studies in a rat model have revealed that levels of urinary exosomal AQP-1 and AQP-2 protein and mRNA were reduced in animals with ischemia/reperfusion-induced AKI (Sonoda et al., 2009; Asvapromtada et al., 2018). The gene discussed is AQP1; the disease is acute kidney injury.